A lump of space detritus a mile across, hitting Earth at around 15 miles per second, would release energy equivalent to a million megatons of TNT, or a hundred million Hiroshima bombs. Computations of the effect of such a blast suggest global catastrophe. No matter where ground zero was located, we’d all be in deep trouble.

You may think this is just theory, but astronomers have seen such a cataclysm, on another planet. Inmid-1994, the 20-odd pieces of a broken-up comet called Shoemaker-Levy 9 slammed into Jupiter. The black eyes that the planet received had areas ranging up to four times the surface area of Earth. And the largest of the comet fragments responsible were only a third of a mile in size.

We know also that such things have occurred on our deceptively docile planet. Geologists have so far identified more than 250 impact craters spread over the continents. On Earth, unlike on the dead, pock-marked moon, active geology and atmospheric weathering erode craters relatively quickly. In any case, 70 per cent of the globe is ocean.

But geologists have estimated how often Earth suffers a cataclysmic impact energetic enough to disrupt the climate globally. Astronomers like myself have made similar estimates from studying asteroids and comets in space.

Our answers agree. Once every 100,000 to 500,000 years, we can expect a major impact, sufficiently powerful to cause the deaths of perhaps half of humankind. That may seem like a comforting answer, but it implies, say, 2.5 billion deaths every 250,000 years, or ten thousand deaths per year, taken as a global long-term average.

Smaller events occur more often. The last really significant one was in 1908, when an asteroid 50 or 60 yards across blew up in the atmosphere above Siberia. This is what usually happens, deceiving us in several ways. For one, it leaves no crater. For another, by exploding at an altitude of a few miles (when the shock of its hypervelocity plummet into the atmosphere causes the rock to shatter into pieces) the object actually causes maximum damage across a wide area. In the Siberian case, it was over a largely uninhabited region. But the flash from the 15 megaton explosion ignited the forest instantaneously, and the following blast (taking 20 to 30 seconds to reach the ground) then blew out the fire and blasted flat the trees over an area of a thousand square miles. We expect such events about once a century; on average. If the next one were to occur over Marble Arch, the whole of London out to the M25 would be razed to the ground.

It is true that you are more likely to die in a car accident than in an asteroid impact. But you are less likely to die in an air crash, where the chances are one in 30,000 against one in 10,000 for an asteroid.

These are averages: a commercial pilot is obviously more at risk from an air crash and an inhabitant of Sydney, San Francisco, Lisbon or any other coastal region facing a large ocean is more at risk from an asteroid because of the phenomenal tsunamis that oceanic impacts produce.

At present, there is not much we can do about the smaller asteroids that hit Earth. Less than about 100 yards in size, these are too difficult to spot, without spending high sums of money. In any case, the annualised death rate they cause is low (around a hundred people per year, globally).

The very large objects (bigger than three miles in size) induce the most damage, but their rate of impact is so low that, again, the annualised death rate is low. You are unlikely to die in a mass extinction event of the sort that hit the dinosaurs.

The most dangerous asteroids are those close to the threshold for causing a global catastrophe, which we define as being an event that would kill at least a quarter to a half of humanity. The size of object that would cause such a calamity is uncertain, because it depends on the impact speed, density and where it hits. But a diameter of about a mile is in the right ballpark. If there is one of that dimension lurking around with our number on it, then we’d better find it soon.

To be conservative, we might take our size limit to be half a mile. (Later, we might set our sights on still smaller objects — the ones that could obliterate a country but not a continent.) Such half-mile asteroids strike Earth only once per 100,000 years, on average. Thus the chance of one being due within the next century is only one in a thousand. And that is the only period of interest to us: we’ll let our great-great-grandchildren look after themselves.

What we need to do, then, is to carry out a surveillance programme aimed at finding all these moderate-sized and larger asteroids, and map their orbits so as to answer one vital question: is there an impact due soon?

If there is, then the odds are that we will have years of warning time, and so we should be able to knock it off course. As they say in the movies, we have the technology — but we hope we won’t have to use it.

A parallel here is with cancer screening. It costs relatively little, and most likely you will not contract the disease in question. But if you do, then your survival depends upon an early diagnosis. None of the solutions to a cancer diagnosis is pleasant: chemotherapy, operative intervention, radiotherapy. The same is true for asteroids. Nuclear weapons provide the only known way of giving the offending object a shove (although in a quite different way from what you will see in the movies).

There is also a parallel in terms of cost. Develop cancer and the expense of tackling it is of no consequence: it’s either your bank balance and mortgage or your life. Similarly, if we found an asteroid likely to hit us in, say, 23 years’ time, then the entire global product would not be too much to spend. We would be staring down the barrel of a gun.

So the essential thing is to give ourselves enough warning time. I first wrote to the British government on this subject more than 11 years ago, when I was operating the only southern hemisphere asteroid search project, at the Anglo-Australian Observatory in New South Wales. The only thing to have changed since then is that the Australian government has closed down that programme, to the dismay of researchers around the world.

The result is that about a third of the sky is being ignored — and it would be more if the Americans could not see some way south with their telescopes in Hawaii.

Here in the UK, despite much posturing, the government has done nothing. The UK government’s task force on potentially hazardous near-Earth objects filed its report two years ago: it had a set of 14 recommendations, leading off with the need for a dedicated southern hemisphere search telescope to complement America’s efforts.

None of those recommendations has yet been implemented. Not a single Earth-approaching asteroid has been spotted by any British search team. Nor have we contributed anything to the mathematical effort to track the routes of potentially hazardous asteroids.

By comparison, the five search projects in the US are finding near-Earth asteroids at a combined rate of about one per night. Japan also has a search project up and running. Italy is a world leader in the dynamical studies.

I know this all sounds like science fiction. I know you think we have more important concerns. Indeed, most likely we have. But if, to our considerable misfortune, there is a mile-wide lump of celestial rock that the clockwork of the heavens has designated to slam into our planet any time soon, then there is no greater problem that humanity faces: not war, not famine, not disease.

To tackle that rock, if it exists, it is vital we find it soon. We have all our eggs in this one little basket we call Earth. We must safeguard it for future generations.

THE boreal forests of Siberia, known as the taiga, account for about 30% of the world’s forests. Their role as a carbon dioxide sink is vital to the prevention of global warming. The taiga is the earth’s lungs. In recent years, however, frequent forest fires have been lowering the taiga’s capacity to absorb carbon dioxide from the atmosphere. Figure 1 shows how much forested land has been lost worldwide between 1964 and 1994. Although much is heard about deforestation in the Amazon region of South America, because forest regrowth is swift there, the cumulative loss of forests in the Amazon is no more than 10% of the loss in Russia (mainly Siberia). In the 30 years represented in Figure 1, forests covering an area 2.5 times that of Japan’s territory were destroyed in the northern regions of the Northern Hemisphere, and Siberia was the main site of forest loss. The main cause of deforestation was forest fires (Figure 2).

Forest fires in the Siberian taiga cause a whole range of environmental and ecological changes and the effects the fires will have on global warming are a great source of concern. Since 1998, a team of Japanese and Russian scientists including the author has been conducting research on the effects of Siberian forest fires on global warming.

Forest Fires and Carbon Dioxide

Because of the sheer vastness of the Siberian taiga, it is difficult to pinpoint the location of forest fires. Thus, we have developed a method of locating forest fires and measuring their expansion in real time using NOAA satellite image resolution technology. The AVHRR (Advanced Very High Resolution Radiometer) sensor detects unusual increases in the temperature of the earth’s surface and discriminates between clouds and forest fire smoke to detect and locate the outbreak of forest fires. Figure 3 shows the distribution of forest fires in far eastern Siberia in 1998 as identified by the NOAA AVHRR system.

Because the fires often break out simultaneously and many occur along roads and rivers, it is assumed that they are caused by human error or activity. According to Russian statistics, around 80% of forest fires are caused by man. The number of fires and the area burned varies year to year due to weather conditions, but it is estimated that the average annual loss over the past 20 years is around 3 million hectares.

Not only do forest fires release carbon dioxide directly into the atmosphere, but they also cause the functional loss of forest’s photosynthesis when the forests burn. Thus, forest fires decrease the amount of carbon dioxide that the taiga can absorb by both direct and indirect means. In order to quantify the decline in carbon dioxide absorption, our research team built an observation tower in the eastern Siberian taiga from which to record long-term changes in the carbon dioxide flux and the energy-mass flux (Figure 4).

We compared the carbon dioxide flux for forests before and after burning or cutting (Columns A and B in Figure 5) with undisturbed forests (Column C). Figure 5 shows quantitatively how disturbance of the forest ecosystem converts forests from net carbon dioxide sinks to net carbon dioxide releasers.

The upper layer of Siberia’s permafrost contains high concentrations of methane gas that was generated earlier in the earth’s history and locked in the frozen soil. Figure 6 shows the concentration of methane gas and carbon dioxide in air bubbles trapped in the upper part of the permafrost. While the concentration of methane gas in the atmosphere today is 1.8 ppm, methane concentration in air bubbles in the permafrost is several thousand times higher. Where this methane gas originated is not yet clearly understood, but scientists have recently discovered that methane-generating bacteria live in the 40,000-year-old permafrost and that the bacteria are capable of producing methane under the low temperature conditions found there.

It is possible that global warming will further activate these methane-producing bacteria and accelerate the rate at which methane is added to the atmosphere.

In the aftermath of a forest fire, the heat-balance at the ground surface is thrown into disarray, and large-scale thawing of the permafrost occurs. This releases large amounts of methane gas into the atmosphere. Methane has a much more powerful greenhouse effect than carbon dioxide.

The effects on global warming caused by forest fires in the taiga are cumulative and they continue long after the fires are extinguished.

Controlling Global Warming

The effects of Siberia’s frequent forest fires on global warming are revealed by Read More >>

A whopping 45% of normal adults snore. That is a significant number! That means that in almost half the households in America, someone is lacking some serious sleep. In most cases it is the spouse or significant other of the person snoring, this can lead to marriage and relationship problems. Many couples will sleep in separate bedrooms if the problem cannot be resolved. Not only is snoring an annoyance, it can be a sign of larger lurking health issues. 75% of the people who snore are actually experiencing obstructive sleep apnea. Sleep apnea causes the individual to stop breathing for a short period of time during sleep. Incidentally, this can lead to an increased risk of developing worse health conditions.

Before you begin treating your snoring problem, be sure to be accessed by a doctor to determine the issue that might be the cause of the snoring. If given the green light there are many anti snoring devices available on the market. You can experiment which one works for you.

Anti-snoring mouthpieces have been proven very effective in treating snoring and mild to moderate cases of sleep apnea. In addition, they can be an added benefit to help a person avoid wearing Read More >>

There is a lot of data recovery software on the market that may or may not benefit your situation if you have deleted your files for any reason or if they got deleted by accident and you want them back. On the other hand is a lot of cheap data recovery software that can actually help you recover your files and save you a lot of money in doing so.

The first that is considered the best cheap data recovery software on the market for 2015 is STELLAR PHOENIX. This software maintains top marks with its home version. It can give very good results when it comes to normal deletes or accidental formatting.

Another good software that is also cheap is Data Rescue PC; this software is a very good one and has very minor limitations such as limits to the total number of recovered files and the way it sorts them.

Then comes some software of higher value but a lower overall rating, which are also very good to recover data. These include GetDataBack, Ontrack EasyRecovery.

Finally R-Studio is worth a mention, and might be considered the second best after STELLAR PHOENIX, except for its exceedingly high price.

Is External Hard Drive Repair Even Possible?

A lot of people confuse hard drive damage with hard drive destruction. Hard drive damage happens everyday and can be fixed usually by using the right tools and software to retrieve the lost data. All that is needed to be done is to perform an external hard drive repair using software or to hire an external hard drive repair specialist that will hopefully bring back all your data intact. The matter of retrieving data is nonnegotiable; the problem lies in how much of the data is safe and how much is corrupted.

Some software nowadays makes any external hard drive repair a simple operation and some of these tools are even free to try. But you will have to buy these products if you want to get more advanced features. Using these tools, data recovery has never been easier. After using such tools, all what is left is to pray that all of your data is safe and that your file system can be restored correctly. Of course with lost structure, data can never be retrieved correctly nor can it be fixed with any software.

What Can Cause Hard Drive Failures

Everything we do might lead to hard disk failures; sometimes even without us knowing. This is why if your company needs to save on hard drive recovery costs. Some hard drive failures might be caused by accidents at work (they can be prevented). When transferring a computer from one department to another, a computer may be dropped. Then, the hard drive is damaged in the process.

The way a worker or a person carries themselves around computers can also increase the potential for data loss. You need to understand that drinking beverages around a laptop is not advised. Sometimes, you can easily short circuit the motherboard and destroy the hard drive in case of a spillage. Always keep your beverages at a safe distance from the laptop.

As a company, make sure that your employees are well trained to handle their assigned computers. Companies with incompetent workers are likely to raise their overall hard drive recovery costs. Many of these workers might visit websites or download files that have viruses. A hard disk failure is not always about the hardware; there is also the software part of failure. Viruses are a leading cause of file loss, and they must be avoided if at all possible.